Backfire

In her seventh appearance (after A Safe Place to Die), Anna Peters is a well-established heroine and businesswoman. Here the savvy, efficient Peters, a PI in Washington, D.C., is hired anonymously to prove the innocence of one Maria Rivas. A companion/nurse from Guatemala, Maria has been accused of setting the blaze that killed her employer, the ailing heiress Helena Skane. Was Maria the murderer? Or could it have been Joseph Skane, Helena's husband, the crass owner of the Beefeater's restaurant chain? Peters's task is complicated by the fact that Maria has not spoken since the night of the murder. Law sets up the case briskly, describing with gusto the struggle between new and old money, the questionable taste of ``the Skane family compound'' and the family itself. But the plot slips quickly into the predictable, and Law leaves hanging a number of details, including the fate of the killer. (Dec.)